Calibration system and method for whole angle gyroscope

Abstract

According to one aspect, embodiments herein provide a whole angle gyroscope comprising a central point, at least one mass arranged symmetrically about the central point, a plurality of transducers, each configured to perform at least one of driving and sensing motion of the at least one mass, and a processor coupled to the plurality of transducers, the processor configured to operate the plurality of transducers to drive the at least one mass in at least a first vibratory mode and a second vibratory mode, identify a rate dead zone of the whole angle gyroscope, and operate the plurality of transducers to apply a force to the at least one mass to reduce the identified rate dead zone of the whole angle gyroscope.

What is claimed is: 
     
       1. A whole angle gyroscope comprising:
 a central point; 
 at least one mass arranged symmetrically about the central point; 
 a plurality of transducers, each configured to perform at least one of driving and sensing motion of the at least one mass; and 
 a processor coupled to the plurality of transducers, the processor configured to:
 operate the plurality of transducers to drive the at least one mass in at least a first vibratory mode and a second vibratory mode; 
 identify a rate dead zone of the whole angle gyroscope; and 
 operate the plurality of transducers to apply a force to the at least one mass to reduce the identified rate dead zone of the whole angle gyroscope. 
 
 
     
     
       2. The whole angle gyroscope of  claim 1 , wherein in identifying the rate dead zone of the whole angle gyroscope, the processor is further configured to generate a motion model of the whole angle gyroscope and identify the rate dead zone based on the motion model. 
     
     
       3. The whole angle gyroscope of  claim 2 , wherein in operating the plurality of transducers to apply the force to the at least one mass, the processor is further configured to calibrate coefficients of the motion model to operate the plurality of transducers to apply the force to the at least one mass. 
     
     
       4. The whole angle gyroscope of  claim 3 , wherein in calibrating the coefficients of the motion model, the processor is further configured to perform multiple iterations of the coefficient calibration. 
     
     
       5. The whole angle gyroscope of  claim 1 , wherein the processor is a Field Programmable Gate Array (FPGA). 
     
     
       6. The whole angle gyroscope of  claim 1 , wherein each transducer is located at a periphery of the at least one mass. 
     
     
       7. The whole angle gyroscope of  claim 1 , wherein the processor is further configured to operate the plurality of transducers to drive the at least one mass in an n=2 vibratory mode. 
     
     
       8. The whole angle gyroscope of  claim 7 , wherein the processor is further configured to operate the plurality of transducers to drive motion of the at least one mass such that a total vibrational energy is maintained across the first vibratory mode and the second vibratory mode and to sense a distribution of energy between the first vibratory mode and the second vibratory mode. 
     
     
       9. The whole angle gyroscope of  claim 8 , wherein the plurality of transducers is further configured to provide signals to the processor based on the sensed distribution of motion between the first vibratory mode and the second vibratory mode, and
 wherein the processor is further configured to calculate an angle of rotation of the whole angle gyroscope based on the signals. 
 
     
     
       10. The whole angle gyroscope of  claim 1 , wherein the at least one mass comprises a plurality of masses, wherein the central point comprises a central anchor, wherein the whole angle gyroscope further comprises:
 a plurality of internal flexures, wherein each mass of the plurality of masses is coupled to the central anchor via at least one of the plurality of internal flexures and is configured to translate in a plane of the whole angle gyroscope; 
 a plurality of mass-to-mass couplers, each mass-to-mass coupler coupled between two adjacent masses of the plurality of masses; and 
 a plurality of transducers, each configured to perform at least one of driving and sensing motion of a corresponding one of the plurality of masses, and 
 wherein the processor is further configured to:
 operate the plurality of transducers to drive the plurality of masses in at least the first vibratory mode and the second vibratory mode; and 
 operate the plurality of transducers to apply the force to the plurality of masses to reduce the identified rate dead zone of the whole angle gyroscope. 
 
 
     
     
       11. The whole angle gyroscope of  claim 10 , wherein each mass-to-mass coupler includes a bar coupled to each adjacent mass via a flexural hinge, wherein the bar is configured to operate such that circumferential motion of one of the two adjacent masses of the plurality of masses to which it is coupled depends on radial motion of the other one of the two adjacent masses. 
     
     
       12. The whole angle gyroscope of  claim 11 , further comprising:
 a plurality of outside anchors; 
 a plurality of outside shuttles, each located at a periphery of a corresponding one of the plurality of masses; and 
 a plurality of outside flexures; 
 wherein each mass of the plurality of masses is suspended between the central anchor and the plurality of outside anchors via the plurality of internal flexures and the plurality of outside flexures; and 
 wherein each one of the plurality of outside shuttles is configured to restrict rotation of its corresponding one of the plurality of masses. 
 
     
     
       13. The whole angle gyroscope of  claim 12 , further comprising a plurality of internal shuttles, each one of the plurality of internal shuttles coupled between the central anchor and a corresponding one of the plurality of masses and configured to restrict rotation of its corresponding one of the plurality of masses. 
     
     
       14. The whole angle gyroscope of  claim 10 , further comprising a plurality of angled electrodes, each angled electrode coupled to a corresponding one of the plurality of masses and configured to trim the cross spring term of the corresponding one of the plurality of masses. 
     
     
       15. The whole angle gyroscope of  claim 1 , wherein the whole angle gyroscope is a Microelectromechanical System (MEMS) based gyroscope. 
     
     
       16. A method of operating a whole angle gyroscope comprising a central point, at least one mass arranged symmetrically about the central point, and a plurality of transducers, each configured to perform at least one of driving and sensing motion of the at least one mass, wherein the method comprises:
 driving, with the plurality of transducers, the at least one mass in at least a first vibratory mode and a second vibratory mode; 
 identifying a rate dead zone of the whole angle gyroscope; and 
 applying, with the plurality of transducers, a force to the at least one mass to reduce the identified rate dead zone of the whole angle gyroscope. 
 
     
     
       17. The method of  claim 16 , wherein identifying the rate dead zone comprises generating a motion model of the whole angle gyroscope and identifying the rate dead zone based on the motion model. 
     
     
       18. The method of  claim 17 , wherein applying the force to the at least one mass comprises calibrating coefficients of the motion model to operate the plurality of transducers to apply the force to the at least one mass. 
     
     
       19. The whole angle gyroscope of  claim 18 , wherein calibrating the coefficients of the motion model comprises performing multiple iterations of the coefficient calibration. 
     
     
       20. A whole angle gyroscope comprising:
 a central point; 
 at least one mass arranged symmetrically about the central point; 
 a plurality of transducers, each configured to perform at least one of driving and sensing motion of the at least one mass; and 
 means for driving the at least one mass in an n=2 vibratory mode, for identifying an angle of rotation of the whole angle gyroscope, and for reducing a rate dead zone of the whole angle gyroscope.